Intake valve for lessening accumulation of high boiling fraction from fuel

ABSTRACT

An intake valve for a combustion engine includes a valve guide having a bore and a lower end surface surrounding the bore, and a valve stem having an upper valve stem portion moving up and down within the bore of the valve guide and a valve at the lower end of the stem. A valve guide shield is carried by the valve stem below the upper valve stem portion that moves up and down within the bore to shield the upper valve stem portion from high boiling fraction material from the fuel to lessen the accumulation of high boiling fraction between the valve stem and the valve guide.

FIELD OF THE INVENTION

The present invention relates to an internal combustion engine and more particularly provides an intake valve that lessens the accumulation within a valve guide of high boiling fraction materials of the fuel.

BACKGROUND OF THE INVENTION

A gasoline-fueled spark-ignition combustion engine traditionally has the fuel introduced into the intake system either through a carburetor or a port fuel injector. Some fuels contain high boiling materials, or fractions, such as polymer fuel additives or gum, and some of the high boiling fractions have a high viscosity, which generally increases exponentially with a decrease in temperature. Consequently, after an engine cools down, an accumulation of high viscosity high boiling fraction on the intake valve surfaces may result. Accordingly, there is a need in the art for an intake system in a combustion engine that may lessen the accumulation of high boiling fraction on intake valve surfaces.

SUMMARY OF THE INVENTION

An intake valve for a combustion engine includes a valve guide having a bore and a lower end surface surrounding the bore, and a valve stem having an upper valve stem portion moving up and down within the bore of the valve guide and a valve at the lower end of the stem. A valve guide shield is carried by the valve stem below the upper valve stem portion that moves up and down within the bore to shield the upper valve stem portion from high boiling fraction material from the fuel to lessen the accumulation of high boiling fraction between the valve stem and the valve guide.

Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

FIG. 1 depicts a combustion engine system in accordance with an embodiment of the invention; and,

FIG. 2 is an enlarged fragment of FIG. 1, showing the valve in the closed and open positions.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

The following description of certain exemplary embodiments is exemplary in nature and is not intended to limit the invention, its application, or uses.

FIG. 1 is an exemplary embodiment of a combustion system 100 for a combustion engine having a cylinder 105 and a piston 1 10 defining a combustion chamber 107, an intake port 115, an exhaust port 120, a fuel supply 125, such as a fuel injector for example, an intake valve 200, and an exhaust valve 300. Intake valve 200 includes a valve stem 205, and a valve head 210 (also referred to as a valve tulip) that has a seating surface 212 that seats against an intake valve seat 117 at intake port 115 during the opening and closing action of intake valve 200. Surrounding valve stem 205 is a valve guide 230 having a bore 232 that is dimensioned in close relationship with an outer surface 207 of the valve stem 205 for guiding the movement of valve stem 205 during the opening and closing action of intake valve 200. The valve guide 230 has a lower end surface 252 that extends into the intake port 115 as seen in FIG. 1.

Referring to FIG. 1, at the top of valve guide 230 is a valve seal 235 for controlling the flow of oil from an oil reservoir, generally depicted as 130 in the combustion engine, for providing lubrication of the valve stem 205 and valve guide 230. An upper end 208 of valve stem 205 is arranged in mechanical communication with a valve cam (not shown) of the combustion engine for driving intake valve 200 to an open position. Intake valve 200 is driven to a closed position by the action of a valve spring 215.

An operational cycle of combustion system 100 begins with intake valve 200 being closed, that is, with seating surface 212 seated against valve seat 117, as shown in FIG. 1, and fuel injector 125 providing a supply of fuel to intake port 1 15 where it is mixed with air. As shown in FIG. 1, spray 135 of the fuel is directed toward valve stem 205 and valve tulip 210. In response to intake valve 200 being opened via the valve cam, the fuel and air mixture is permitted to enter combustion chamber 107. Thereafter valve spring 215 drives intake valve 200 to the closed position and timed combustion and exhaust take place.

During the combustion cycle, the outer surface 207 of the valve stem 205 is at an elevated temperature, which results in the evaporation of the low boiling fraction of the fuel and the adhesion to outer surface 207 of the high boiling fraction of the fuel. With an upper portion of valve stem 205 moving in and out of valve guide 230, over many combustion cycles some of the high boiling fraction on valve stem 205 may be pushed into the clearance space between the outer surface 207 of valve stem 205 and the bore 232 of the valve guide 230.

According to the invention, the accumulation of the high boiling fraction (also referred to as residue or gum) at the clearance space may be lessened by providing a valve stem shield 250 on the valve stem 205. As best seen in FIG. 2, the valve stem shield 250 is a circular disc shaped ring that moves up and down with the valve stem 205 as the valve is opened and closed through travel “D”. The valve stem shield 250 can be formed integrally with the valve stem 205 during the manufacture of the intake valve 200. Alternatively, the valve stem shield 250 can be a separately manufactured hollow circular disc or washer that is fitted onto the valve stem 205 and then welded or mechanically attached to the valve stem 205. The disc shape washer can be flat, or concave, or convex.

As seen in FIG. 2, the valve stem shield 250 is located at a location along the length of the valve stem 205 such that when the intake valve 200 is in the closed position, as indicated in solid lines of FIG. 2, the valve stem shield 250 will closely approach the lower surface 252 of the valve guide 230, but not so close as to create contact. Then, as the intake valve 200 moves downward to its open position, the valve stem shield 250 will move downwardly with the valve stem 205 to the phantom line indicated position of FIG. 2. The diameter of the valve stem shield 250 is approximately the same as the outer diameter of the valve guide lower end face 252.

In view of the foregoing, it will be seen and understood that the valve stem shield 250 will reduce the accumulation of high boiling fraction at the clearance space between the valve stem 205 and the valve guide 230. In particular, the valve stem shield 250 will act as a shield to fend off the high boiling fraction material that might otherwise be deposited on that portion of the length of the valve stem 205 that will travel up and down in valve guide 230. The valve stem shield 250 is effective both during the injection of fuel while the intake valve 200 is closed, and during the opening of the intake valve 200, when there is blowback of high boiling fracture material onto the valve stem 205. Depending upon the dimensions and geometry of the arrangement, it may be desirable to have the valve stem shield 250 be of a diameter greater than the diameter of the valve guide lower face 232, particularly in fending off the blowback of combustion products.

While an embodiment of the invention has been described employing a fuel injection system for supplying fuel, it will be appreciated that the scope of the invention is not so limited, and that the invention may also apply to a carburetor fuel delivery system. Although the drawings herein depict a linear piston and cylinder arrangement as an exemplary combustion system for the combustion engine, it will be appreciated that the disclosed invention may also be applicable to other combustion systems, such as a rotary combustion system employed in a rotary combustion engine for example. And although the drawings show the example of a valve stem shield 250 that is a flat shape, the shield 250 can be either concave or convex. 

1. An intake valve for a combustion engine comprising: a valve guide having a bore and a lower end surface surrounding the bore; a valve stem having an upper valve stem portion moving up and down within the bore of the valve guide and a valve at the lower end of the stem; and a valve guide shield carried by the valve stem below the upper valve stem portion moving up and down within the bore to shield the upper valve stem portion from high boiling fraction material from the fuel to lessen the accumulation of high boiling fraction between the valve stem and the valve guide.
 2. The intake valve of claim 1 further comprising the valve stem shield being of integral one-piece construction with the valve stem.
 3. The intake valve of claim 1 further comprising the valve stem shield being a hollow washer that seats on the valve stem and is attached thereto.
 4. The intake valve of claim 3 further comprising the valve stem shield being attached to the valve stem by welding.
 5. The intake valve of claim 1 further comprising said valve guide shield closely approaching the lower end face of the valve guide when the valve stem is moved up.
 6. The intake valve of claim 1 further comprising said valve guide shield having a diameter that is sufficient to shield the upper portion of the valve stem from blow back of combustion product toward the valve when the valve is in the open position.
 7. The intake valve of claim 1 further comprising said valve guide shield being located on the valve stem so as to closely approach the lower end face of the valve guide when the valve stem is moved up, and being of a diameter sufficient to shield the upper portion of the valve stem from blowback of the combustion products when the valve stem is lowered to open the valve.
 8. An intake valve for a combustion engine comprising: a valve guide having a bore and a lower end surface surrounding the bore; a valve stem having an upper valve stem portion moving up and down within the bore of the valve guide and a valve at the lower end of the stem; and a disc-shaped valve guide shield carried by the valve stem below the upper valve stem portion moving up and down within the bore, said valve guide shield being located on the valve stem so as to approach the lower end face of the valve guide when the valve stem is moved up to open the valve, and being of a diameter sufficient to shield the upper portion of the valve stem from blowback of the combustion products when the valve stem is lowered to open the valve.
 9. The intake valve of claim 8 further comprising the valve stem shield being of integral one-piece construction with the valve stem.
 10. The intake valve of claim 8 further comprising the valve stem shield being a hollow washer that seats on the valve stem and is attached thereto.
 11. The intake valve of claim 8 further comprising the valve stem shield being a disc shaped washer that fits onto the stem, and a weld that attaches the washer to the valve stem.
 12. An intake valve for a combustion engine comprising: a valve guide having a bore and a lower end surface surrounding the bore; a valve stem having an upper valve stem portion moving up and down within the bore of the valve guide and a valve at the lower end of the stem; and a valve guide shield of disc shape formed in one-piece with the valve stem below the upper valve stem portion to shield the upper valve stem portion from high boiling fraction material from the fuel to lessen the accumulation of high boiling fraction between the valve stem and the valve guide.
 13. The intake valve of claim 12 further comprising said valve guide shield closely approaching the lower end face of the valve guide when the valve stem is moved up.
 14. The intake valve of claim 12 further comprising said valve guide shield having a diameter that is sufficient to shield the upper portion of the valve stem from blow back of combustion product toward the valve when the valve is in the open position.
 15. The intake valve of claim 12 further comprising said valve guide shield being located on the valve stem so as to closely approach the lower end face of the valve guide when the valve stem is moved up, and being of a diameter sufficient to shield the supper portion of the valve stem from blowback of the combustion products when the valve stem is lowered to open the valve. 